Conventionally, in, e.g., a manufacturing process of a semiconductor device, a substrate processing apparatus for processing a substrate while supplying a gas in a shower shape through a shower head disposed to face a substrate has been used as a processing apparatus for processing a substrate such as a semiconductor wafer or a glass substrate for use in a liquid crystal display or the like.
For example, in a plasma processing apparatus for performing plasma processing such as an etching process or a film forming process on a substrate disposed in a processing chamber by using a plasma generated from a processing gas in the processing chamber, the shower head forms an electrode facing a mounting table for mounting thereon the substrate. Further, a predetermined processing gas is supplied in a shower shape through the shower head, and is discharged through a periphery of the mounting table (substrate) toward a lower portion of the processing chamber. Furthermore, a plasma of the processing gas is generated by a high frequency power applied to a space between the shower head and the mounting table.
Further, there is known a plasma processing apparatus in which a gas is discharged through the periphery of the shower head toward an upper portion of the processing chamber (see, e.g., Japanese Patent Publication No. 2662365).
In the above prior arts, a gas is arranged to be discharged at the periphery of the mounting table (substrate) toward the lower portion of the processing chamber or at the periphery of the shower head toward the upper portion of the processing chamber. Therefore, the gas supplied through the shower head flows from a central portion to a peripheral portion of the substrate, thereby making a processing state at the central portion of the substrate different from that at the peripheral portion of the substrate, resulting in deteriorating in-plane uniformity of the processing. Further, a gas exhaust channel needs to be provided at a periphery of the mounting table (substrate) or that of the shower head, so that the processing chamber is considerably scaled up compared to the substrate accommodated therein, which makes it difficult to scale down the entire apparatus. Moreover, a pressure in the processing space is controlled by adjusting an opening degree of the gas exhaust unit. As a result, responsiveness becomes poor, or fine adjustment becomes difficult.